MUI

Material UI (the `@mui/material` package, from the MUI organization) is a React component library implementing Google's Material Design system as an independent implementation - not a wrapper around Google's own code. It's been developed for more than a decade with contributions from a large open-source community, and its core set of components can be extended with MUI X, a separate suite of more complex components (data grids, date pickers, charts) for advanced use cases.

It's a fit for React teams that want a mature, ready-made set of accessible UI components following Material Design conventions, rather than building a design system's components from scratch.